The present invention relates to pipeline repair and/or reinforcement and in particular to installation assemblies for pipeline liners, pipeline liners and methods for installing pipeline liners.
Pipeline liners are often used to repair and/or reinforce ruptured or weak areas in pipeline networks such as sewer systems and the like. There are many disadvantages associated with the current methods of installing pipeline liners.
Pipeline liners for constant or variable diameter pipelines are typically installed using bladder systems. During installation of a pipeline liner, the bladder system is inflated to expand the pipeline liner and force it against the interior surface of the pipeline. The pipeline liner is then allowed to cure against the inner wall of the pipeline. Current bladder systems require pipeline access at the location that is to be repaired or re-enforced. Gaining access to a particular pipeline location can be difficult. Additional labor is required because the pipeline must be excavated in order to gain access at the desired location.
It is also not uncommon for a pipeline to vary in diameter along its length. Such an in-line transition in pipeline size has traditionally made it necessary for technicians to excavate at the transition point in order to install a pipeline liner. Although, expandable pipeline liner materials that accommodate the varying diameter of a pipeline are currently available, these materials become thinner when they expand to larger diameters. As a result larger diameter sections of pipelines end up with a sub standard repair because there is not enough pipeline liner material to give it strength.
Another difficult area of pipelines to repair or re-enforce is the T-junction between a main pipe to a lateral line. These junctions are typically the weakest joints in pipeline systems. Therefore, lining of these junctions is common. Current pipeline liners for T-junctions are difficult to install and require multiple steps, thus making the installation procedure time consuming for technicians. As will be appreciated, improvements to pipeline liner installation assemblies, pipeline liners and methods of installing the same are desired.
It is therefore an object of the present invention to obviate or mitigate at least one of the above described disadvantages.
According to one aspect of the present invention there is provided an installation assembly for installing a liner in a pipeline, said installation assembly comprising:
a bladder assembly to be inserted into a liner, said bladder assembly including:
an inflatable inner bladder having an installation end and a retrieval end and defining an internal reservoir; and
an outer bladder surrounding said inner bladder at least along a portion of the length thereof, said outer bladder having an end coupled to said inner bladder adjacent said installation end;
a fluid passage coupled to said inner bladder, said fluid passage for introducing fluid into said internal reservoir to inflate said inner bladder and expand a liner carried by said bladder assembly so that said liner can be brought into firm contact with an interior surface of said pipeline; and
a retrieval line for removing said bladder assembly from said pipeline, said retrieval line being coupled to the retrieval end of said inner bladder so that when said bladder assembly is removed from said liner with said inner bladder deflated, said outer bladder separates from said liner and inverts.
Preferably, the installation assembly further comprises an inversion element received by the inner bladder and the outer bladder adjacent the installation end. The inner and outer bladders are coupled to a portion of the inversion element. It is also preferred that the installation assembly further comprises an installation cable coupled to the inversion element external to the bladder assembly. The installation cable is used to pull the bladder assembly to a desired location within the pipeline.
In a preferred embodiment, the fluid passage is a hose coupled to the retrieval end of the inner bladder and constitutes the retrieval line. It is also preferred that the installation assembly further include an air pump coupled to the hose to inflate and evacuate the inner bladder.
According to another aspect of the present invention there is provided a method of installing a liner in a pipeline comprising the steps of:
pulling a bladder assembly carrying a wetted liner in one direction into position in said pipeline, said bladder assembly including an inner bladder having an installation end and a retrieval end and an outer bladder surrounding said inner bladder and contacting an inner surface of said liner, said outer bladder having one end coupled to said inner bladder adjacent said installation end and an opposite free end;
introducing fluid into said inner bladder to inflate said inner bladder so that said bladder assembly expands to bring said liner into firm contact with an interior surface of said pipeline.
maintaining said bladder assembly in an inflated condition for a time period sufficient for said liner to cure;
deflating said inner bladder; and
retrieving said bladder assembly from said pipeline by pulling said bladder assembly in an opposite direction via said inner bladder so that when said inner bladder moves out of said liner, said outer bladder separates from said liner and inverts.
According to another aspect of the present invention there is provided a liner for a variable diameter pipeline comprising:
an expandable tube formed from a rolled sheet of flexible material and having an overlapping portion therein; and
a web secured to said tube to maintain said tube in a rolled condition, said web defining an expandable joint running generally the length of said tube.
Preferably, the overlapping portion is sized to cover the web when the tube is in an expanded condition. It is also preferred that the web is formed of expandable material and extends between an edge of the tube and a main portion of the tube to trap the overlapping portion within the tube.
According to another aspect of the present invention there is provided an installation assembly for installing a liner at the junction between a main pipe and a lateral pipe, said installation assembly comprising:
an inflatable bladder assembly for carrying a liner, said bladder assembly including a main portion and a lateral portion and defining an internal reservoir;
a carrier coupled to the main portion of said bladder assembly;
a fluid passage coupled to said bladder assembly to introduce fluid into said internal reservoir and inflate the main and lateral portions of said bladder assembly thereby to expand said liner so that when said lateral portion extends into said lateral pipe and said main portion is in said main pipe, said liner is brought into contact with the interior of said main and lateral pipes and conforms to the shape of said junction.
Preferably, the lateral portion of the bladder system includes an inner bladder and an outer bladder. The outer bladder extends at least along a portion of the length of the inner bladder. The outer and inner bladders are coupled adjacent a distal end of the lateral portion. It is also preferred that the carrier extends through the main portion of the bladder system. A second installation cable is coupled to a leading edge of the carrier and a retrieval carrier is coupled to a trailing edge of the carrier. It is also preferred that the fluid passage is in the form of a hose having one end received by the carrier.
According to another aspect of the present invention there is a method of installing a liner having main and lateral portions at a junction between main and lateral pipes, said method comprising the steps of:
pulling a bladder assembly carrying a wetted liner into said pipeline, said bladder assembly including a main portion and a lateral portion and defining an internal reservoir, said bladder assembly being positioned so that the lateral portion thereof extends into said lateral pipe and with the main portion thereof positioned in said main pipe;
introducing fluid into said bladder assembly to inflate said bladder assembly so that said bladder assembly expands to bring said liner into firm contact with interior surfaces of the main and lateral pipes and conform said liner to the shape of said junction;
maintaining said bladder assembly in an inflated condition for a time period sufficient for said liner to cure;
deflating said bladder assembly; and
retrieving said bladder assembly from said pipeline by pulling said bladder assembly from said liner.
The present invention provides advantages in that liners can be installed in pipelines in a relatively simple manner without requiring excavation to access the pipelines. The present invention also provides advantages in that liners can be installed at junctions between main and lateral pipes in a single application. The present invention provides further advantages in that variable diameter pipelines can be repaired and/or reinforced while ensuring high integrity linings.